Yes, you can edit your own comments or entries after posting in Answers, Discussions, or Notebooks, but you can't edit the title of the Answer, Discussion, or Notebook.
How to Edit Your Post
1. After you have submitted an entry, just hit the "Edit" button.
2. After you have edited the text, press the "Update" button.That's it! The post has been edited. There is now a yellow "Edited" icon on the top left of your post to indicate that it has been edited.
Please be careful with what you post in your Notebook, Answers or Discussions as they are visible to everyone and they link back to your profile.
If you want to figure out how to delete entries, you can do so by following the instructions at the bottom of the page here.